Process for preparation of substituted 3,4-(diphenyl)chromans

ABSTRACT

SUBSTITUTED 3,4-DIPHENYLCHROMANS IN TRANS CONFIGURATION ARE OBTAINED BY A PROCESS WHEREIN A 2M2-BIS(LOWER ALKYL)3 - PHENYL=4-(HYDROXYOHENYL)CHROMENE IS HYDROGENATED, PROVIDNG A CIS-2,2-BIS(LOWER ALKYL)-3-PHENYL-4-(HYDROXYPHENYL)CHROMAN WHICH IS REACTED WITH A PRIMARY, SECONDARY OR TERTIARY LOWER HALOALKYLAMINE TO FORM THE CORRESPONDING CIS-2,2-BIS(LOWER ALKYL)-3-PHENYL-4-(AMINO OR SUBSTITUTED AMINOALKOXYPHENYL)CHROMAN, FOLLOWED BY THE STEP OF TRANSFORMING THE CIS ISOMER TO THE TRANS CONFIGURATION BY MEANS OF A BASE-CATALYZED REARRANGEMENT.

3,822,287 Patented July 2, 1974 UnitedStates Patent 3,822,287 i PROCESS FOR PREPARATION OF SUBSTITUTED 3,4-(DIPHENYL)CHROMANS James W. Bolger, Canoga Park, Calif., assignor to Rexall Drug and Chemical Company No Drawing. Continuation-impart of abandoned application Ser. No. 817,142, Apr. 17, 1969. This application June 8, 1972, Ser. No. 260,849

" Int. Cl. C07d 7/24 U.S. Cl. 260-- 326.5 D N 24 Claims ABSTRACT OF THE DISCLOSURE Substituted 3,4-diphenylchromans in trans configuration are obtainedby a process wherein a 2,2-bis (lower alkyl)- 3 phenyl-4-(hydroxyphenyl)chromene is hydrogenated, providing a cis-2,2-bis(lower alkyl)-3-phenyl-4- (hydroxyphenyl)chroman which is reacted with a primary, secondary or tertiary lower haloalkylamine to form the corresponding cis-2,2-b-is(lower alkyl)-3-phenyl-4-(amino or substituted aminoalkoxyphenyl)chroman, followed by the step, of transforming the cis isomer to the trans configuration by means of a base-catalyzed rearrangement.

BACKGROUND OF THE INVENTION This application is a continuation-in-part of my prior copending application for U.S. Letters Patent, Ser. No. 817,142, filed Apr. 17, 1969, now abandoned.

The preparation of compounds prepared by the process of this invention has been previously described in general terms, for example in U.S. Pat. 3,340,276 both cis and trans isomeric forms of these compounds being formed.-

It is suggested these can be separated on the basis of physico-chemical differences." The report of Carney etal J. Med. Chem. 9:516-520, 1966, shows obtaining pure cis and. transisorners of similar compounds by separate preparative techniques. However, the prior art does not describe the preparation of the pure trans isomers of these compounds free from cis isomers, .nor does the prior art. as far asis known suggest chemical conversion or rearrangement of the cis isomer'to the trans'isomer. It is believed to be novel, unobvious and unexpected that the cis isomerscould be converted through the action of catalysts asdescribed herein to pure trans'isOmer. The use of a specific class of catalysts to effect this transformation is the point of novelty of the present invention.

.DETAILED DESCRIPTION OF THE INVENTION This invention relates to a process for the preparation of trans-2,2-bis(lower alkyl)-3-phenyl 4 (substituted aminoor aminoalkoxyphenyl)chromans, and particularly to the step of transforming the cis isomers of these products to the trans configuration by means of a basecatalyzed rearrangement.

The process of the invention is illustrated by the following reaction sequence. The structural formulae are set forth in accordance with accepted practice to indicate isomeric forms.

wherein R is lower alkyl, R is lower alkoxy, lower alkyl,-

. halogen or trifiuoromethyl, Alk is lower alkylene, and in the group NR R the R and R substituents are in dependently hydrogen or lower alkyl, or, taken together with the nitrogen atom to which they are atta'ched, form' a 5- or 6-membered nitrogen-containing heterocyclic ring wherein oneof the carbon atoms may be replaced by an' oxygen atom, said heterocyclic ring being selected from the group consisting of pyrrolidino, morpholino, piperidino, piperazino, 4-lower alkylpiperazino and 4-phenylpiperazino, and X is halogen.

As used throughout this application, the terms lower alky and lower alkoxy embrace both straight and branched chain alkyl and alkoxy radicals, respectively,

containing from 1 to 6 carbon atoms, for example, but without limitation, methyl, ethyl, n-propyl, isopropyl, n-' I .butyl, tert-butyl, n-am'yl, sec-amyl, n-hexyl, 2-ethylb1'1tyl,

2,3-dimethylbutyl and the like in the case of lower alkoxy, and the term lower alkylene embraces Fbo'th' straight and branched chain alkylene radicals containing from 2 to 6 carbon atoms, for example, but without limitation, ethylene (CH CH n-propylene tert-butylene -CH C CH n-amylene butylene omc rrgcHzcHvcHzcHz-o, 2,3-dimethylbutylene (CH CH(CH )CH(CH )CH and the like.

The trans-2,2-bis(1ower alkyl)-3-phenyl-4-(substituted aminoor aminoalkoxyphenyl)chromans prepared by the process of this invention possess valuable pharmacological activity as post-coital anti-fertility agents; see, for example, U.S. Pats. 3,340,226, 3,340,277 and 3,535,344. A method for testing chemical compounds to establish their value as anti-fertility agents is described in J. Reproduction and Fertility, vol. 5, page 239 1963 The cis isomers appear to have significantly lower or even no physiological activity for the stated purpose.

The process is particularly useful for compounds of high activity wherein R is 7-methoxy.

Compounds wherein Alk is ethylene form a preferred subclass.

Another subclass of compounds are those wherein [R and R are methyl or ethyl, and most preferred is methyl.

Another preferred subclass is compounds wherein R and R together form a pyrrolidino ring.

The presently preferred compounds for preparation by the process of the invention are:

trans-2,2-dimethyl-7-methoxy 3 -phenyl-4- [p (l9-pyrrolidinoethoxy)phenyl]chroman and trans-2,2-diethyl-7-methoxy-3 phenyl-4[p-(fl-pyrrolidinoethoxy) phenyl]chroman.

Broadly speaking, the process as shown is carried out to produce the cis isomers of the product. The product is then treated by the novel catalytic reaction of the invention to convert the cis isomer to the trans configuration.

Step ('1) of the process is the hydrogenation of a 2,2- .bis(lower alkyl)-3-phenyl-4 (hydroxyphenyl)chromene. Such chromenes are conveniently prepared from 4-(acetoxyphenyl) 3-phenyl-coumarins by basic hydrolysis of the acetoxy group followed by reaction with an appropriate lower alkyl magnesium halide Grignard reagent.

The hydrogenation is carried out in the presence of a I,

ingly substituted cis-2,2 -bis(lower alkyl) 3 phenyl 4- (hydroxyphenyl)chroman.

Step (2) of the process is the reaction of the hydroxy group of the product of step l) with an appropriate lower haloalkylamine of the formula Rl XAlkN wherein X, Alk, R and R are as previously defined. Among the suitable reactants that may be used in carrying out the process according to the present invention are unsubstituted (i.e. primary) lower haloalkylamines, for example 2-ch'loroethylamine, 3-bromo-propylamine and the like; secondary lower haloalkylamines, for example 2- chloro-N-methylethylamine, 3bromo-N-ethylpropylamine and the like; tertiary lower haloal kylamines, for example 2-chloro- N,N-diethylethylamine, 3-bromo-N ethyl I methylethylamine and the like; and the lower alkyl halides of saturated cyclic organic bases, for example N- (2- chloroethyl)-pyrrolidine, N-(2-chloroethyl)piperidine, N- 2-chloroethyl) N'-phenylpiperazine, N-(3-chloropropyl) morpholine, N-(Z-bromoethyl)piperidine, N-(2 bromoethyl) piperazine, N-(2-ch'loroethyl)-N'-methyl piperazine and the like. Y

The reaction is carried out in an inert organic solvent medium, such as diethyl ketone, acetone, methanol ethanol, is'opropanol or mixtures thereof, dimethylformamide, dimethylsulfoxide and the like, in the presence of a base, for example potassium carbonate, sodium hydroxide, sodium hydride and the like, and at the reflux temperature of the solvent used.

The cis product of the reaction may be recovered by conventional procedures of isolation and purification, as the free base or as an acid addition salt (forexample as the hydrochloride).

Step (3) is carried out in the presence of a basic catalyst. Through the use of the catalyst, the cis isomeric compound is transformed to the corresponding compound in the trans configuration by means of a base-catalyzed rearrangement. Only certain strong organometallic bases have been found to be useful. The rearrangement is carried out by treatment of the cis compound with an organolithium compound such as phenyl lithium or a lower alkyl lithium such as n-bu-tyl lithium; or by treatment with an alkali metal alkoxide such as potassium tert-butoxide. The reaction is carried out in the presence of a potentiating solvent such as dimethyl sulfoxide, dimethylformamide and the like. The preferred treatment is with n-butyl lithium in dimethyl sulfoxide. The product of the reaction is preferably recovered as the free base and then optionally converted to one of its acid addition salts.

EXAMPLE 1 (a) cis-2,2-Dimethyl-4-(p-hydroxyphenyl)-7-methoxy-3- phenylchroman rolidinoethoxy)phenyl]chroman hydrochloride The hydroxyphenylchroman from ,(a) (2.8 g., 0.0078

. mole), \N-(Q-chloroethyl)pyrrolidine hydrochloride (2.0

g., 0.117 mole), ground anhydrous potassium carbonate (6.0 g., 0.9434 mole) and acetone (250 ml.) were refluxed together for 40 hours. The reaction mixture was filtered, and the filtrate was concentrated to an oil. The oil was taken up in diethyl ether, and the ether solution was washed with aqueous sodium hydroxide, then with water,-

sis-2,Z-DimethylJ-methoxy-B-phenyl-4- [p-(B-pyrrolidino- I ethoxy) phenyl] chroman cis-2,-2-Dimethyl-4-l(p-hydroxyphenyl) 7 methoxy-3- phenylchroman 50 g., 0118 mole), prepared as described in Example 1(a), and an aqueous solution of sodium hydroxide (13.9 g. in 40 ml. of water) was added to isopropanol ("250 ml.). After stirring for '15 minutes to effect partial solution, N-('2-chloroethyl)pyrrolidine hydrochloride (23.5 g., 0.139 mole) was added, and the resulting mixture was stirred for four hours at 50 C. The reaction mixture was cooled and then diluted with 500 ml. of Water and extracted twice with diethyl ether. The ether extract was washed with water and then extracted four times with aqueous 1 N hydrochloric acid. The acidified aqueous extract was made basic with 50 percent aqueous sodium hydroxide solution to yield the white:

solid product, m.p. l 1-7.5-119 C.

dimethylsulfoxide (100 ml.) were placed 'iu'a dried flask fitted with a stirrer and nitrogen sparge tube. 'n Butyl lithrum solution (20 ml., 1.6 'm in hexane) was then added overabo'ut 10 minutes. Deep red 'color'formed and then 'slowly'faded to a dullr'ed' brown. There Wass'ome warming observed, but no cooling was'req'uiredfiAfter stirring for 1.5 hours thereaction mixture was decomposed with water (20 ml.). The resulting solution was further diluted with water (200 ml.), and then the product was extracted into diethyl ether (four 100 ml. ether extracts). The ether extract was washed twice with 50 ml. portions of water, ,7

dried over anhydrous sodium sulfate and then evaporated in vacuo. The resulting oil was triturated with diethyl ether-petroleum (30-60'1C.) ether mixture to yield a white crystalline solid, m.p. -70 C.

The solid was recrystallized from ether-petroleum (30- pared according'to the method of Example 1(a), and'a solution of sodium hydroxidle (1.82 g. in 5 ml.' of water) were added to isopropanol (33 ml.). After stirring for 15 minutes, N-(Z-chIorOethyl')-pyrrolidine hydrochloride (3.08 g.) was added, andthe resulting mixture was stirred'at 50 for four hours. To the cooled reaction mix;

ture was then' added 67 ml. ofw'ater. The produce precipitated after one additional hour 'of stirring, i'nl'p. 130- 131 C.

Analysis: Calculated a. (s mmo c, 79.13; H, 8.09; I, a,

N, 2.88. Found: c, 79.59; H, 8.21; N, 2.87.

EXAMPLE 5 traits-2,2-Diethyl-7-methoidy-3-phenyl-4-[p-(B-pyrrolidinoethoxy)phenyl] chroman hydrochloride Anhydrous dimethyl sulfoxide (80 ml.) and the cis compound from Example 4 (7.5 g., 0.015 mole) were placed in a dry flask with a stirrer and nitrogen sparge tube. n- Butyl lithium solution (16 ml., 1.6 m. in hexane) was then added over a 10 minuteperiod. After stirring for 90 minutes, the reaction mixture was decomposed by adding 16 ml. of water. The mixture was then dilutedfurther with water (160 ml.) and then extracted twice with diethyl ether. The ether extracts were washed with water, dried over anhydrous magnesium sulfate, treated with gaseous hydrogen chloride, stirred and cooled to givethe trans product, m.p. 226-227 C.

Analysis: Calculated for C H NO Cl: -C, 73.61; H, 7.72; N, 2.68; Cl, 6.79. Found: C, 73.59; H, 7.63; N, 2.57; CI, 6.97. v v cis, trans Isomer mixtures of substituted 3,4-diphenylchromans may be converted to substantially pure trans isomer by the process of step (3) of theinvention.

Using the method of Example 5, the following known cis, trans isomer mixturesof substituted 3,4-diphenylehromans, prepared in accordance with the disclosure of U.S. Pat. 3,340,276 are converted to the corresponding pure trans isomer. 9 a 1 I cis, trans 3-(4-methyl-phenyl)-4-{4-[2 (lfpiperidino) p ethyl]oxyphenyl}-chroman, 1 cis, trans 3-(4 rnethoxy-phnyD-4-[-(Z+N,N-dimethy1{ cis, trans 3-(4-chloro-phenyl)-4-{4-[2-(l-pyrrolidino) ethyl]-oxyphenyl}-chroman, c is trans 7-chloro-4- [3-chloro-4-(2-N,N-diethylaminojethyl)oxyphenyl]-3-phenylchroman, cis, trans '4 -"[4- (2 N,N-diethylaminoethyl) oxyphenyl] 7-methoxy-3-phenylchroman, and cis, trans 5,7-dimethoxy-4-{4-[2-(4-methy1-1-piperazino) ethyl]oxyphenyl}-chroman.

What is claimed is: 1. A process for preparing substituted trans-3,4-(diphenyl)chromans of the formula wherein R is lower alkyl, R is lower alkoxy, lower alkyl, halogen or trifluoromethyl, Alk is lower alkylene, and in the group NR R the R and R substituents are independently hydrogen or lower alkyl, or, together with the nitrogen atom to which they are attached, form a 5- or 6-membered nitrogen-containing heterocyclic ring wherein one of the carbon atoms may be replaced by anioxygen atom, said heterocyclic ring being selected from the group consisting of pyrrolidino, morpholino, piperidino, piperazino, 4-lower alkylpiperazino and 4- phenylpiperazino; said process comprising (a) the catalytic hydrogenation of a substituted 3,4-

I (diphenyl)chromene compound of the formula wherein R and R are as defined above;

(b) reaction of the so-formed substituted cis-3,4-(diphenyl)chroman product of step (a) with a compound of the formula XAlkNR R wherein X is halogemand Alk, R and R are as defined above, in the presence of a base, to form a compound of the formula 7 solvent, to catalyze rearrangement thereof" wholly to the corresponding trans product. e 2. A process for preparing substituted t'rans-7-lower wherein R is lower alkyl, Alk is lower alkylene, and in the group NR R and R and R substituents are independently hydrogen or lower alkyl, or, together with the nitrogen atom to which they are attached, form a 5- or 6-membered nitrogen-containing heterocyclic ring wherein one of the carbon atoms may be replaced by an oxygen atom, said heterocyclic ring being selected from the group consisting of pyrrolidino, morpholino, piperidino, piperwherein R, Alk, R and R are as defined above; and (c) contacting said substituted cis-7-lower alkoxy-2,2-

di-lower alkyl-3,4-diphenylchroman with a .strongly basic catalyst selected from the group consisting of (1) organo-lithium compounds, and (2) alkali metal alkoxides, in the presence of an inert organic solvent, to catalyze rearrangement thereof wholly to the corresponding substituted trans-7-lower alkoXy-2,2- di-lower-alkyl-3,4-diphenylchroman.

3. Process according to claim 2 wherein said 8. The preparation of trans-2,2-dimethyl-3-phenyl-4- [p-(fl-pyrrolidinoethoxy)phenyl]-7-methoxychroman according to claim 4.

9. The preparation of trans-2,2-diethyl-3-phenyl-4-[p- (fl pyrrolidinoethoxy)phenyl] -7-methoxychr0man according to claim 4.

; 10. 'In the process for producing trans-2,2-bis(lower alkyl)-3-phenyl-4- (substituted aminoor aminoalkoxyphenyl)chroma'ns,' the step which comprises contacting a compound of the formula O-AIk-NR R wherein R islower alkyl, R is lower alkoxy, lower alkyl, halogen or trifiuoromethyl, Alk is lower alkylene, and in the group NR R the R and R substituents are independently hydrogen or lower alkyl, or, together with the nitrogen atom to which they are attached, form a 5- or 6-membered nitrogen-containing heterocyclic ring wherein one of the carbon atoms may be replaced by an oxygen atom, said heterocyclic ring being selected from the group consisting of pyrrolidino, morpholino, piperidino, piperazino,4-lower alkylpiperazino and 4-phenylpiper'azino, with a strongly basic catalyst selected from the group consisting of 1) organ'o-lithium compounds, and (2) alkali metal alkoxides, in the presence of an inert organic solvent, to catalyze rearrangement thereof wholly to the corresponding trans product of the formula I ohm-Nam by rearrangementaccording to claim 13.

16. Process according toclaim '1 wherein the strongly basic catalyst is selected from the group consisting of (1) phenyl lithium compounds, (2) loweralkyl lithium compounds, and (3) alkali metal alkoxides.

17. Process according to claim 2 whereinthe strongly basic ,catalyst is selected from the group consisting of (l) phenyl lithium compounds, (2) lower alkyl lithium compounds, and.(3) alkali metal alkoxides. Q

18. Step according to claim 10 wherein the strongly basic catalystis selected from the group consisting of (1) phenyl lithium compounds, (2)" lower alkyl lithium compounds, and (3) alkali metal alkoxides.

19. Step according to claim 1 wherein the strongly basic catalyst is selected from the group consisting of (1) phenyl lithium, and (2) lower alkyl lithiums.

20. Step according to claim 2 wherein the strongly basic catalyst is selected from the group consisting of (1) phenyl lithium, and (2) lower alkyl lithiums.

21. Step according to claim 10 wherein the strongly basic catalyst is selected from the group consisting of (l) phenyl lithium, and (2) lower alkyl lithiums.

22. Step according to claim 1 wherein the strongly basic catalyst is an alkali metal alkoxide.

23. Step according to claim 2 wherein the strongly basic catalyst is an alkali metal alkoxide.

24. Step according to claim 10 wherein the strongly basic catalyst is an alkali metal alkoxide,

10 References Cited UNITED STATES PATENTS 3,535,344 10/1970 Irmscher et al. 260-345.2

OTHER REFERENCES Gilman, Organic Chemistry (adv.), 1938, vol. 1, pp.

JOSEPH A. NARCAVAGE, Primary Examiner US. Cl. X.R.

260-247] A, 268 BC, 293.58, 345.2, 999 

